This invention relates to a coupling for use in an inboard/outboard engine and more particularly to an improved coupling arrangement suitable for use in a marine outboard drive.
A very popular type of propulsion device used in watercraft is the so-called inboard/outboard drive in which an inboard mounted engine drives an outboard mounted propulsion unit which is steerable and tiltable like an outboard motor. These types of drives have a number of advantages but do present certain design problems. Specifically, it is the normal practice to couple the output shaft of the engine through its flywheel to an input shaft of the outboard drive which extends through the hull and transom of the watercraft into the outboard drive unit. Because of the mounting arrangement and problems attendant therewith, it is desirable if this coupling will accommodate misalignment between the engine shaft and the input shaft. A wide variety of couplings have been proposed for this purpose, however, they all have some disadvantages, as will now be described.
FIG. 1 shows one conventional type of coupling, indicated generally by the reference numeral 11, that serves the purpose of coupling an engine output shaft 12 to the input shaft 13 of the outboard drive unit. The engine output shaft 12 has a flange portion 14 to which a flywheel 15 is affixed in a known manner, as by means of bolts 16.
The coupling 11 is comprised of a generally barrel shaped section 17 that has a correspondingly shaped recess 18 and a flange portion 19 that is affixed to the flywheel 13 and engine output shaft 12 by the bolts 16. An elastomeric sleeve 21 is received within the recess 18 and supports an internally splined member 22. The internally splined member 22 receives a splined end 23 of the input shaft 13.
The disadvantage with this type of construction is first that the bolting arrangement for securing the coupling 11 to the flywheel 19 requires a spacing 1 between the barrel shaped portion 17 and the flange 19 so as to access the bolts 16. As a result, the device tends to be quite long and also requires somewhat intricate assembly because of the difficulty in accessing the bolt 16.
Another form of prior art coupling is shown in FIG. 2 and incorporates a coupling 51 for coupling an engine driven flywheel 52 to the outboard drive input shaft 53. The coupling 51 includes a torsional vibration damper 54 for absorbing torsional vibrations but has substantially no construction that will accommodate angular or axial misalignments between the engine output shaft and the outboard drive input shaft 53.
FIG. 3 shows yet another prior art type of coupling arrangement wherein a coupling 101 is provided for connection to a flywheel 102 which is, in turn, affixed to the engine output shaft 103. The coupling 101 couples the input shaft 104 of the outboard drive unit to the engine shaft 103.
In accordance with this type of coupling, the coupling is formed from a sheet metal member 105 that has a generally barrel shaped configuration and defines a recess 106 in which an elastic sleeve 107 is formed. The sleeve 107 supports an internally splined member 108 that is coupled to splines 109 of the outboard drive input shaft 104. The member 105 also has a flange 111 that is affixed, as by bolts 112 to the flywheel so as to complete the coupling.
The disadvantage with this type of construction is that it is rather expensive to manufacture. That is, the member 105 must be formed by means of an internal die so as to form the barrel shaped recess 106 and, accordingly, the device is relatively expensive, particularly where small scale production is necessary that does not justify the high tooling costs.
It is, therefore, a principal object of this invention to provide an improved, compact and low cost coupling for an inboard/outboard drive.
It is a further object of this invention to provide a low cost, easily fabricated and yet highly versatile coupling for an inboard/outboard drive that will accommodate large variations in angular position between the coupled shafts.